1. Field of the Invention
The present invention relates to an image processing device that processes an image of the inside of a living body, an image processing method, an image processing program, and an endoscope system.
2. Description of the Related Art
With the advent of capsule endoscopes, which are swallowable endoscopes having an imaging function and a wireless communication function built into a capsule case, endoscope systems, which display images of the inside of an organ (hereinafter referred to as in-vivo images), obtained by a capsule endoscope being introduced into an organ of a subject, have been proposed in the endoscope field. Capsule endoscopes are swallowed by a subject in order to observe the inside of organs of a subject including a patient, then move due to peristaltic motion through the inside of the organs, and are finally excreted out of the body of the subject. The capsule endoscope captures in-vivo images, for example, at an interval of 0.5 seconds during the period of time from being swallowed by the subject to being excreted out of the body of the subject, and sequentially transmits the obtained in-vivo images to the outside using wireless communication.
Each of the in-vivo images transmitted in order of time sequence by the capsule endoscope in this manner using wireless communication is sequentially received by a receiving device outside of the body of the subject. The receiving device stores a group of in-vivo images received from the capsule endoscope in order of time sequence on a storage medium which is inserted in advance. After the groups of in-vivo images obtained by the capsule endoscope have been sufficiently stored, the storage medium in the receiving device is removed from the receiving device, and is inserted into an image display device. The image display device imports the groups of in-vivo images on the inserted storage medium, and sequentially displays each obtained in-vivo image on a display. A user such as a doctor or a nurse observes each in-vivo image displayed sequentially on the image display device, and can observe (inspect) the inside of the organ of the subject through this observation of the in-vivo image.
At this point, to facilitate observation by the user of polyp, lesions, ulcers, or the like, endoscope systems have been proposed which generate and display an image showing a protrusion portion and depression part on the surface of biological tissue, based on the image imaged by the capsule endoscope (for example, refer to Japanese Laid-open Patent Publication No. 2003-265405). With the endoscope system, two images are obtained by causing a capsule endoscope to operate two illumination units during separate periods using a capsule endoscope in which two illumination units are provided at different positions. Then, with the endoscope system, a distance of the surface of biological tissue from the capsule endoscope is calculated by processing the two images using a distance difference between the two illuminations which are at different positions. The endoscope system generates, on the basis of a calculation result, an image including three-dimensional information stereoscopically showing a protrusion portion and a depression part on the surface of biological tissue, or surface orientation information.